Ultrasound elastography in tendon pathology: state of the art

Chinese Ultrasound Doctors Association Guideline on Operational Standards for 2-D Shear Wave Elastography Examination of Musculoskeletal Tissues

The Ultrasound Physician Branch of the Chinese Medical Doctor Association sought to develop evidence-based recommendations on the operational standards for 2-D shear wave elastography examination of musculoskeletal tissues. A consensus panel of 22 Chinese musculoskeletal ultrasound experts reviewed current scientific evidence and proposed a set of 12 recommendations for 13 key issues, including instruments, operating methods, influencing factors and image interpretation. A final consensus was reached through discussion and voting. On the basis of research evidence and expert opinions, the strength of recommendation for each proposition was assessed using a visual analog scale, while further emphasizing the best available evidence during the question-and-answer session. These expert consensus guidelines encourage facilitation of the standardization of clinical practices for collecting and reporting shear wave elastography data.

Ultrasonographic evaluation of the masseter muscle in patients with temporomandibular joint degeneration

Purpose

Sonographic elastography can be used to evaluate the hardness of muscle tissue through the application of compression. Strain elastography gauges hardness through the comparison of echo sets before and after compression. This study utilized ultrasonography to measure the thickness and hardness of the masseter muscle in individuals with temporomandibular joint (TMJ) osteoarthritis.

Materials and Methods

This study included 40 patients who presented with joint pain and were diagnosed with TMJ osteoarthritis via diagnostic cone-beam computed tomography, along with 40 healthy individuals. The thickness and hardness of each individual's masseter muscle were evaluated both at rest and at maximum bite using ultrasonography. The Mann-Whitney U test and the chi-square test were employed for statistical analysis, with the significance level set at P<0.05.

Results

The mean thickness of the resting masseter muscle was 0.91 cm in patients with osteoarthritis, versus 1.00 cm in healthy individuals. The mean thickness of the masseter muscle at maximum bite was 1.28 cm in osteoarthritis patients and 1.36 cm in healthy individuals. The mean masseter elasticity index ratio at maximum bite was 4.51 in patients with osteoarthritis and 3.16 in healthy controls. Significant differences were observed between patients with osteoarthritis and healthy controls in both the masseter muscle thickness and the masseter elasticity index ratio, at rest and at maximum bite (P<0.05).

Conclusion

The thickness of the masseter muscle in patients with TMJ osteoarthritis was less than that in healthy controls. Additionally, the hardness of the masseter muscle was greater in patients with TMJ osteoarthritis.

Visualization of Human Hand Tendon Mechanical Anisotropy in 3-D Using High- Frequency Dual-Direction Shear Wave Imaging

High-resolution ultrasound shear wave elastography has been used to determine the mechanical properties of hand tendons. However, because of fiber orientation, tendons have anisotropic properties; this results in differences in shear wave velocity (SWV) between ultrasound scanning cross sections. Rotating transducers can be used to achieve full-angle scanning. However, this technique is inconvenient to implement in clinical settings. Therefore, in this study, high-frequency ultrasound (HFUS) dual-direction shear wave imaging (DDSWI) based on two external vibrators was used to create both transverse and longitudinal shear waves in the human flexor carpi radialis tendon. SWV maps from two directions were obtained using 40-MHz ultrafast imaging at the same scanning cross section. The anisotropic map was calculated pixel by pixel, and 3-D information was obtained using mechanical scanning. A standard phantom experiment was then conducted to verify the performance of the proposed HFUS DDSWI technique. Human studies were also conducted where volunteers assumed three hand postures: relaxed (Rel), full fist (FF), and tabletop (TT). The experimental results indicated that both the transverse and longitudinal SWVs increased due to tendon flexion. The transverse SWV surpassed the longitudinal SWV in all cases. The average anisotropic ratios for the Rel, FF, and TT hand postures were 1.78, 2.01, and 2.21, respectively. Both the transverse and the longitudinal SWVs were higher at the central region of the tendon than at the surrounding region. In conclusion, the proposed HFUS DDSWI technique is a high-resolution imaging technique capable of characterizing the anisotropic properties of tendons in clinical applications.

Regional assessments of supraspinatus muscle stiffness in normal adults using shear wave elastography

Objectives

To provide normal references for regional shear wave elastography assessments of supraspinatus muscle in a population.

Methods

Shear wave elastography images of supraspinatus muscles were evaluated on 100 shoulders of 50 normal adults in a fixed position with 30° shoulder abduction both at rest and contraction. Shear wave velocity values and activity values of intramuscular tendon, anterior superficial, anterior deep, posterior superficial, posterior deep, and central subregions were measured. The possible differences in hand dominance, sexes, stratified age groups, and internal muscular-component subregions were discussed.

Results

The results showed that shear wave velocity values at rest and activity values differed significantly among supraspinatus muscular-component subregions. Shear wave velocity values at rest were normally highest in posterior deep and lowest in central subregions, whereas activity values were highest in central subregions. The results also showed evaluation of the intramuscular tendon using shear wave elastography to be practicable. The differences in shear wave velocity values at rest between the dominant and nondominant sides were not significant in each subregion, while the values at rest of the majority of subregions were significantly greater in males than in females. Stratified by age groups of 10 years, the shear wave velocity values at rest of some subregions tended to increase with age, with uncorrelations possibly related to insufficient sample sizes and different intensities of limb activities.

Conclusions

This study suggested that regional assessments of supraspinatus stiffness using shear wave elastography are feasible, with further research supporting that it can provide information on the surgery, training, and rehabilitation of rotator cuff tears.

Imaging biomarkers in the idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are a group of acquired muscle diseases with muscle inflammation, weakness, and other extra-muscular manifestations. IIMs can significantly impact the quality of life, and management of IIMs often requires a multi-disciplinary approach. Imaging biomarkers have become an integral part of the management of IIMs. Magnetic resonance imaging (MRI), muscle ultrasound, electrical impedance myography (EIM), and positron emission tomography (PET) are the most widely used imaging technologies in IIMs. They can help make the diagnosis and assess the burden of muscle damage and treatment response. MRI is the most widely used imaging biomarker of IIMs and can assess a large volume of muscle tissue but is limited by availability and cost. Muscle ultrasound and EIM are easy to administer and can even be performed in the clinical setting, but they need further validation. These technologies may complement muscle strength testing and laboratory studies and provide an objective assessment of muscle health in IIMs. Furthermore, this is a rapidly progressing field, and new advances are going to equip care providers with a better objective assessment of IIMS and eventually improve patient management. This review discusses the current state and future direction of imaging biomarkers in IIMs.

Ultrasound Elastography for Hand Soft Tissue Assessment

Over the past decade, ultrasound elastography has emerged as a new technique for measuring soft tissue properties. Real-time, noninvasive, and quantitative evaluations of tissue stiffness have improved and aid in the assessment of normal and pathological conditions. Specifically, its use has substantially increased in the evaluation of muscle, tendon, and ligament properties. In this review, the authors describe the principles of elastography and present different techniques including strain elastography and shear-wave elastography; discuss their applications for assessing soft tissues in the hand before, during, and postsurgeries; present the strengths and limitations of their measurement capabilities; and describe directions for future research.

The fate of sutures post rotator cuff repair

BACKGROUND

Ultrasonographic imaging has been widely used as a diagnostic tool for rotator cuff tears. Several studies have explored the changes in rotator cuff tendon morphology after arthroscopic cuff repair; however, none have addressed the fate of sutures. The aim of this study was to determine (1) if the sutures migrate through the tendon during the postoperative healing period in patients who have had arthroscopic rotator cuff repair; (2) if the sutures do migrate, the time point at which it does; and (3) if the quality of the tendon, in terms of tendon stiffness, modulus of elasticity, bursal thickness, and anatomic footprint, affects suture migration.

METHODS

This was a prospective study involving 21 patients who had primary arthroscopic rotator cuff repair performed by a single surgeon. All patients were assessed at 8 days, 6 weeks, 12 weeks, and 24 weeks postrepair; during each assessment, patients underwent an ultrasonographic examination (using a Siemens ACUSON S3000 ultrasonographic system, following a standardized protocol), where supraspinatus tendon thickness and thickness of tendon tissues below and above the suture were measured. Measurements of anatomic footprint, bursal thickness, tendon stiffness, and modulus of elasticity were obtained to assess tendon quality.

RESULTS

Of the 21 participants, 14 (67%) had full-thickness tears and 7 (33%) had partial-thickness tears. Between the 12th- and 24th-week follow-up, 2 patients' tendons were found to be not intact. Within the first 12 weeks of the postrepair healing period, the sutures migrated inferiorly, through to the middle of the tendon at the footprint-articular junction (ie, ratio of tendon tissue thickness below the suture to the total tendon thickness = 0.5) (P = .03). The mean anatomic footprint increased from 8.4 ± 1.6 mm to 9.1 ± 1.2 mm between 8 days and 6 weeks (P = .04); bursal thickness decreased during the 24-week period from 1.5 ± 0.9 mm to 0.7 ± 0.4 mm (P = .005); tendon modulus of elasticity increased from 154 ± 75 kPa to 205 ± 96 kPa between 8 days and 24 weeks (P = .05).

DISCUSSION

This is the first study to investigate suture position and migration post arthroscopic rotator cuff repair. The findings of this study suggest that sutures migrating to the middle of the tendon during the postoperative healing process is a normal phenomenon observed on ultrasonography.

Evaluation of Tendon Disorders With Ultrasonography and Elastography

The frequency of musculoskeletal system ultrasonography (US) has increased over time. The most common reason for musculoskeletal US is the evaluation of tendons. The superficial location of tendons makes US the most suitable diagnostic tool, and US is generally the initial imaging modality for tendon disorders. The primary advantages of US are its low cost, easy accessibility, rapidity, repeatability, freedom from x-rays, and enabling of a dynamic inspection. In addition, Doppler US and elastography can be performed simultaneously with US. We aimed to demonstrate the US and elastographic findings of tendon disorders that we frequently encounter in different regions.

Effects of Loading and Boundary Conditions on the Performance of Ultrasound Compressional Viscoelastography: A Computational Simulation Study to Guide Experimental Design

Most biomaterials and tissues are viscoelastic; thus, evaluating viscoelastic properties is important for numerous biomedical applications. Compressional viscoelastography is an ultrasound imaging technique used for measuring the viscoelastic properties of biomaterials and tissues. It analyzes the creep behavior of a material under an external mechanical compression. The aim of this study is to use finite element analysis to investigate how loading conditions (the distribution of the applied compressional pressure on the surface of the sample) and boundary conditions (the fixation method used to stabilize the sample) can affect the measurement accuracy of compressional viscoelastography. The results show that loading and boundary conditions in computational simulations of compressional viscoelastography can severely affect the measurement accuracy of the viscoelastic properties of materials. The measurement can only be accurate if the compressional pressure is exerted on the entire top surface of the sample, as well as if the bottom of the sample is fixed only along the vertical direction. These findings imply that, in an experimental validation study, the phantom design should take into account that the surface area of the pressure plate must be equal to or larger than that of the top surface of the sample, and the sample should be placed directly on the testing platform without any fixation (such as a sample container). The findings indicate that when applying compressional viscoelastography to real tissues in vivo, consideration should be given to the representative loading and boundary conditions. The findings of the present simulation study will provide a reference for experimental phantom designs regarding loading and boundary conditions, as well as guidance towards validating the experimental results of compressional viscoelastography.

Differences in Achilles tendon stiffness in people with gout: a pilot study

Background

Gout has been associated with weaker foot/leg muscles and altered gait patterns. There is also evidence of on-going foot pain and an increased risk of tendinopathy, with the Achilles and patella tendons most frequently affected in gout. Additionally, the inflammation associated with gout may change tissue elasticity. Ultrasound imaging utilising shear wave elastography (SWE) offers a non-invasive method of quantifying changes in tendon stiffness. SWE findings have not previously been reported in individuals with gout. We sought to determine differences in Achilles tendon stiffness in people with gout compared to controls (non-gout).

Methods

A cross sectional study comparing 24 people with gout and 26 age/sex-matched controls. Clinical and demographic data were collated, and US imaging used to determine tendon thickness, presence of gouty tophi and/or aggregates and levels of angiogenesis. Ten shear wave elastography (SWE) measures were taken along the centre of a longitudinal section of the mid-portion of each Achilles tendon. Prior to data collection, intra-observer error was good (>0.69). Data were summarised using descriptive statistics and a repeated measures ANCOVA was used to compare SWE measures between the two groups for the left and right foot separately after accounting for Body Mass Index (BMI).

Results

A small proportion of those with gout presented with intra-tendon aggregates and/or intra-tendon tophi in one or both tendons. There was no statistically significant difference in tendon thickness between groups. Neo-vascularity was present in a third of gout participants. SWE findings demonstrated significantly reduced tendon stiffness in those with gout compared to controls: right Achilles mdiff =1.04 m/s (95% CI (0.38 to 1.7) p = 0.003 and left Achilles mdiff = 0.7 m/s (95% CI 0.09 to 1.32) p = 0.025. No relationship between the presence of tophi and SWE values were detected.

Conclusion

Subjects with chronic gout show significantly reduced Achilles tendon stiffness compared to non-gout controls. From a clinical standpoint, our findings were similar to SWE measurements in subjects with Achilles tendinopathy and who did not have gout.

Novel Muscle Imaging in Inflammatory Rheumatic Diseases-A Focus on Ultrasound Shear Wave Elastography and Quantitative MRI

In recent years, imaging has played an increasing role in the clinical management of patients with rheumatic diseases with respect to aiding diagnosis, guiding therapy and monitoring disease progression. These roles have been underpinned by research which has enhanced our understanding of disease pathogenesis and pathophysiology of rheumatology conditions, in addition to their key role in outcome measurement in clinical trials. However, compared to joints, imaging research of muscles is less established, despite the fact that muscle symptoms are very common and debilitating in many rheumatic diseases. Recently, it has been shown that even though patients with rheumatoid arthritis may achieve clinical remission, defined by asymptomatic joints, many remain affected by lingering constitutional systemic symptoms like fatigue, tiredness, weakness and myalgia, which may be attributed to changes in the muscles. Recent improvements in imaging technology, coupled with an increasing clinical interest, has started to ignite new interest in the area. This perspective discusses the rationale for using imaging, particularly ultrasound and MRI, for investigating muscle pathology involved in common inflammatory rheumatic diseases. The muscles associated with rheumatic diseases can be affected in many ways, including myositis-an inflammatory muscle condition, and myopathy secondary to medications, such as glucocorticoids. In addition to non-invasive visual assessment of muscles in these conditions, novel imaging techniques like shear wave elastography and quantitative MRI can provide further useful information regarding the physiological and biomechanical status of the muscle.

Current advances and research in ultrasound imaging to the assessment and management of musculoskeletal disorders

Currently evidence-based practice has given scientific weight to the physical therapist profession; it is essential that all medical professional and physical therapists know the usefulness of new tools that optimize the effectiveness of their interventions and allow the growing of the scientific knowledge base. The use of ultrasound imaging (USI) by physiotherapists has evolved in recent years, consolidating as an increasingly standardized technique, low cost compared to other imaging techniques, quickly of execution, feasible and reliable tool. USI offers a wide range of opportunities in clinical practice as well as in different research areas. Therefore, ultrasound has been currently used as a diagnostic tool by physicians and in recent years there has been an expansion of the use of ultrasound equipment by non-physicians professionals such as physical therapist or physical trainers, who incorporates USI as a means of assessing musculoskeletal system architecture and composition, musculoskeletal changes in dysfunction, pain or injury conditions, as an interventional technique assisting echo-guided procedures or using the visual real-time information as a biofeedback in control motor approaches, as guiding tool in clinical decisions as well as to improve the understanding of tissue adaptations to exercise or movement. The purpose of this article is to review and provide an overview about the currently research of the USI applications and their benefits for the diagnosis and management in individuals with musculoskeletal conditions.

In vivo assessment of material properties of muscles and connective tissues around the knee joint based on shear wave elastography

Previous studies on knee biomechanics have mainly focused on the joint structure itself, largely neglecting the material properties of the muscles and connective tissues around the knee joint. Therefore, this study was purposed to conduct a systematic in vivo examination of the material properties of muscles, tendons, and ligaments, and investigated the respective influences of gender and age on the material properties. The participants were 50 healthy males and females within the following four age groups: 21-30 years, 31-40 years, 41-50 years, and above 51 years. The Young's moduli of the muscles, tendons, and ligaments around the knee joint were measured by shear wave elastography (SWE). Analysis of the Young's modulus results showed that excellent repeatability could be achieved by using SWE. For muscles, the intraclass correlation coefficient (ICC) and 95% confidence interval (CI) ranged between 0.952 and 0.987, and 0.923 and 0.992, respectively. The ICC ranged from 0.920 to 0.941, and the 95% CI was between 0.872 and 0.969 for tendons and ligaments. Additionally, the Young's moduli of the muscles, tendons, and ligaments of males were greater than those of females. With the exception for medial patellar retinaculum (MPR), the Young's moduli of other observed tissues decreased with age for both males and females, indicating that age has a significant impact on the Young's moduli of muscles, tendons, and ligaments. Hence, SWE is a reliable and repeatable technique that can be used to assess the Young's moduli of the muscles, tendons, and ligaments around the knee joint. Furthermore, gender and age affects the material properties. The results of this study provide an in vivo database of the material properties of muscles and connective tissues, and thus may prove useful for the prevention and treatment of knee joint injuries and diseases.

Characterization of soft tissue tumours with ultrasound, shear wave elastography and MRI

OBJECTIVE

To predict accurately whether a soft tissue mass was benign or malignant and to characterize its type using ultrasound, shear wave elastography and MRI. We hypothesized that with the addition of shear wave elastography, it would be possible to determine a threshold velocity value to classify a lesion as benign or malignant.

MATERIALS AND METHODS

A total of 151 consecutive, consenting adult patients were prospectively recruited to this study in a tertiary referral musculoskeletal oncology centre. All lesions were assessed with ultrasound, including B mode, Doppler and shear wave elastography measurements. One hundred thirty-eight patients also underwent MRI of the lesion. A histological diagnosis was obtained for all lesions.

RESULTS

Malignant lesions were larger than benign lesions and had a greater Doppler activity. There was no useful threshold shear wave velocity to differentiate between benign and malignant lesions. Longitudinal and transverse shear wave velocities were strongly positively correlated with each other. An inverse correlation was shown with lesion size and depth, regardless of whether it was benign or malignant. A logistic regression model combining the ultrasound and MRI characteristics did not confidently classify a lesion as benign or malignant and was inferior to expert opinion.

CONCLUSION

The strongest predictors of malignancy are large lesion size and high vascularity. The combination of all ultrasound characteristics (including shear wave elastography) and MRI features does not confidently classify a lesion as benign or malignant, and histological diagnosis remains the gold standard.

Muscle-tendon weakness contributes to chronic fatigue syndrome in Gaucher's disease

Background

Chronic fatigue (CFg) is a prevalent symptom in Gaucher disease (GD) at diagnosis (79%) and remains in a quarter of patients after years of therapy. Bone abnormalities are present in over 70% and peripheral neuropathy in about 11% of the patients, which contributes to the disabling and debilitating complications. Our hypothesis is that other factors such as muscle-tendinous weakness could have influence in the development of CFg.

Methods

We have evaluated the fiber structure and elasticity of muscle-tendinous unit by strain-elastography (S-ELA) and analyzed their influence in the CFg. S-ELA study was performed in Achilles tendon in 25 type 1 and two type 3 GD patients, all of them with fatigue and were on enzymatic replacement therapy for mean 13 years; simultaneously, bone marrow burden by MRI and calcaneus ultrasound densitometry were evaluated. Blood cell counts, plasma biomarkers, GBA1 genotyping, and SF36 quality of life scale (QoL) were also performed. Statistical analysis: descriptive and comparative test.

Results

All patients showed a normal Achilles tendinous structure. Abnormal stiff grade 2–3 was found in 17/27 (62.9%); in 11/27 (40.7%) of patients, the alteration was bilateral. There were no correlations between the S-ELA results to other variables; nevertheless, a significant correlation between the degree of tendon hardness and the low score on the QoL scales (p = 0.0035) was found. The S-ELA is a sensitive painless, fast, and low cost method to detect muscle-tendinous subclinical dysfunction that could contribute to CFg in GD. The identification of subclinical tendon alteration would be a sign of alarm, focused on the risk of development of bone complications.

Conclusion

Intratendinous alteration in strain-elastography is an independent variable in GD patients with persistent fatigue.

The value of sonoelastography in the diagnosis of supraspinatus tendinopathy-a comparison study

OBJECTIVE:

This study assessed the association between tendon stiffness on sonoelastography and grades of tendinopathy on MRI in patients with supraspinatus tendinopathy.

METHODS:

25 consecutive adult patients with clinically suspected supraspinatus tendinopathy and no prior history of trauma referred for MRI of the shoulder were selected for this study. The supraspinatus tendinopathy was graded in consonance with MRI findings (Grade I, normal; Grade II, mild tendinopathy; Grade III, moderate tendinopathy; and Grade IV, marked tendinopathy). Strain ratios were evaluated. Spearman rank correlation test was used, to analyze the association of the MRI grade with strain ratios.

RESULTS:

Out of 25 patients, Grade I changes on MRI were found in 5 patients (20.0%), Grade II tendinopathy in 13 patients (52.0%), Grade III in 6 patients (24.0%), and Grade IV in 1 patient (4.0%). The mean sonoelastography strain ratio of supraspinatus tendons were 0.76 ± 0.32 in patients with Grade I, 0.59 ± 0.40 in Grade II, 0.31 ± 0.10 in Grade III and 0.15 ± 0.02 in Grade IV patients respectively. The strain ratios showed good correlation with the MRI grade p < 0.05.

CONCLUSION:

We compared the MRI findings of supraspinatus tendinopathy with sonoelastography strain ratios. Sonoelastography showed good correlation with MRI.

ADVANCES IN KNOWLEDGE:

Sonoelastography in supraspinatus tendinopathy may help in predicting improvement or worsening of the tendon health at the tissue level. Therefore, there is a possibility that it has use in the rehabilitation of professionals suffering from supraspinatus tendinopathy.

Muscle shear wave elastography in idiopathic inflammatory myopathies: a case-control study with MRI correlation

OBJECTIVE

To investigate muscle stiffness in patients with idiopathic inflammatory myopathies (IIM) using shear wave elastography (SWE) and to correlate the results with muscle strength and MRI features of myositis.

MATERIALS AND METHODS

Muscle shear wave velocity (SWV) was measured in 23 active IIM patients (13 females, mean age 50.4 ± 16.1 years) and 23 matched healthy controls (13 females, mean age 50.7 ± 16.2 years). The investigated muscles included the vastus lateralis (VL), rectus femoris (RF), vastus medialis (VM) vastus intermedius (VI), biceps femoris (BF), semitendinosus (ST), semimembranosus (SM) and the biceps brachii (BB) scanned during relaxed resting and passive stretching positions. Participants performed multiple tests to evaluate their muscle strength. IIM patients had a thigh MRI to assess degrees of oedema, fatty infiltration and atrophy.

RESULTS

In the resting position, IIM patients had a 12.9-22.2% significantly lower SWV (p < 0.05) for the quadriceps and hamstrings, but not BB. There was no difference during passive stretching. The SWV for VL, VI and BF showed moderate correlations with the muscle strength tests ranging from r = 0.47 to r = 0.70 (all p < 0.05). Lower SWV was associated with greater MRI scores of oedema (p = 0.001) and atrophy (p = 0.006). However, SWV did not correlate with fatty infiltration (r < 0.3; p = 0.28), creatine kinase (r = 0.28; p = 0.19) or disease duration (r = 0.26; p = 0.24).

CONCLUSION

Shear wave elastography may detect abnormal reduced thigh stiffness in IIM patients. SWE measurements were significantly associated with muscle weakness and MRI signs of oedema and atrophy. Future research should investigate this new technology for monitoring disease activity.

Interobserver variability and stiffness measurements of normal common extensor tendon in healthy volunteers using shear wave elastography

OBJECTIVES

The purposes of our study are to determine the quantitative elasticity values of normal common extensor tendon (CET) and to assess the interobserver variability of stiffness measurements using shear wave elastography (SWE).

MATERIALS AND METHODS

A total of 60 CETs of 30 (15 female, 15 male, mean age 30.2 years) healthy volunteers without any symptoms of lateral epicondylitis were examined by two radiologists. Age, sex, height, weight, body mass index (BMI), and dominant hand of all participants were noted. The first observer performed B-mode and SWE imaging, and the second observer performed only SWE imaging. Tendon thickness and stiffness values in kPa were measured.

RESULTS

The mean thickness of CETs was 3.57 ± 0.36 mm. The mean stiffness values of CETs for two observers were 45.28 ± 9.82 kPa and 45.80 ± 9.72 kPa respectively. Tendon thickness had a weak correlation with weight (r = 0.281, p = 0.03), and moderate correlation with stiffness values (r = 0.429, p < 0.001). The mean interobserver difference of CET stiffness measurements was -0.5% of the mean CET stiffness values. Range of measurement error, defined as 95% limits of agreement, was ±23.5%. There was no significant difference between absolute values of interobserver measurements (p = 0.741).

CONCLUSION

Shear wave elastography is a reproducible imaging technique for the evaluation of CET elasticity and the standard stiffness values of normal CET can be used as reference data to differentiate normal from pathological tissues.

Diabetic Gait Is Not Just Slow Gait: Gait Compensations in Diabetic Neuropathy

BACKGROUND

Neuropathic complications from diabetes mellitus affect multiple nerve types and may manifest in gait. However, gait compensations are still poorly understood, as narrow analyses and lack of speed controls have contributed to conflicting or equivocal results.

PURPOSE

To evaluate gait mechanics and energetics in diabetic peripheral polyneuropathy.

METHODS

Instrumented gait analysis was performed on 14 participants with diabetic peripheral polyneuropathy and 14 matched controls, walking at 1.0 m/s. A full-body model with a multisegment foot was used to calculate inverse dynamics and analyze sagittal plane metrics and time series waveforms across stance phase.

RESULTS

Alterations included increased hip and knee flexion in early stance followed by a prolonged hip extension moment in midstance. Late stance ankle dorsiflexion and power absorption were increased, and final push-off was delayed and truncated.

CONCLUSION

A neuropathic diabetic gait shares important similarities to a mild crouch gait with weakness/dysfunction in the foot and ankle. This study highlights two main compensation mechanisms that have been overlooked in previous literature. First, increased triceps surae stretch in terminal stance may be used to increase proprioception and/or energy storage, while a prolonged hip extension moment in midstance compensates for a limited push-off. These result in an overall workload shift from distal to proximal joints. Clinical assessment, monitoring, and treatment of neuropathy may benefit by focusing on these specific functional alterations.

Classification of Tendon Matrix Change Using Ultrasound Imaging: A Systematic Review and Meta-analysis

Ultrasound imaging (US) is an accurate and reliable method used to diagnose tendinopathy. This systematic review was aimed at identifying common criteria and parameters used to diagnose tendinopathy, the methodological quality of studies and the predictive value of US. Nineteen studies met the inclusion criteria, with the Achilles, quadriceps and patella tendons being investigated. Overall, there was significant heterogeneity between the criteria used to diagnose tendinopathy utilising US. The methodological quality of included studies was "good." Additionally, meta-analysis revealed that US-identified abnormalities were predictive of future symptoms, and classification of tendinopathy using three US defined parameters indicated a higher relative risk of developing clinical tendinopathy compared with the use of two US-defined parameters. Further research into the development of a standardised US criterion that incorporates both clinical and US findings is required to allow for greater consistency in the diagnosis of tendinopathy.

Ultrasound elastography: compression elastography and shear-wave elastography in the assessment of tendon injury

Ultrasound elastography (USE) is a recent technology that has experienced major developments in the past two decades. The assessment of the main mechanical properties of tissues can be made with this technology by characterisation of their response to stress. This article reviews the two major techniques used in musculoskeletal elastography, compression elastography (CE) and shear-wave elastography (SWE), and evaluates the studies published on major electronic databases that use both techniques in the context of tendon pathology. CE accounts for more studies than SWE. The mechanical properties of tendons, particularly their stiffness, may be altered in the presence of tendon injury. CE and SWE have already been used for the assessment of Achilles tendons, patellar tendon, quadriceps tendon, epicondylar tendons and rotator cuff tendons and muscles. Achilles tendinopathy is the most studied tendon injury with USE, including the postoperative period after surgical repair of Achilles rupture tendon. In relation to conventional ultrasound (US), USE potentially increases the sensitivity and diagnostic accuracy in tendinopathy, and can detect pathological changes before they are visible in conventional US imaging. Several technical limitations are recognised, and standardisation is necessary to ensure repeatability and comparability of the results when using these techniques. Still, USE is a promising technique under development and may be used not only to promote an early diagnosis, but also to identify the risk of injury and to support the evaluation of rehabilitation interventions. KEY POINTS: • USE is used for the assessment of the mechanical properties of tissues, including the tendons. • USE increases diagnostic performance when coupled to conventional US imaging modalities. • USE will be useful in early diagnosis, tracking outcomes and monitoring treatments of tendon injury. • Technical issues and lack of standardisation limits USE use in the assessment of tendon injury.

Ultrasound elastography and ultrasound tissue characterisation for tendon evaluation

Ultrasound elastography (UE) and ultrasound tissue characterisation (UTC) are two newer modes of ultrasound (US) which have begun to attract scientific interests as ways to improve tendon characterisation. These modes of US show early promise in improved diagnostic accuracy, prediction of at-risk tendons and prognostication capability beyond conventional grey-scale US. Here, we provide a review of the literature on UE and UTC for Achilles, patellar and rotator cuff tendons.

The translational potential of this article: The present literature indicates that UE and UTC could potentially increase the clinician's ability to accurately diagnose the extent of tendon pathology, including preclinical injury.